Yes I am running 3.1.9 on both devices. The files are on the SD card. My Samsung is rooted and the SD card location is embedded as internal storage. And normally the snippets are working. On my Huawei I put the files into <path to removable sd card>/Android/data/com.zubersoft.mobilesheetspro/files>
Samsung Galaxy Tab S7 FE Android 12
Samsung Note Pro 12.2 LineageOS 14.1
Huawei Media Pad M3 lite Android 7
Samsung Note Pro 12.2 LineageOS 14.1
Huawei Media Pad M3 lite Android 7